Abstract

Data intensive applications on clusters often require requests quickly be sent to the node managing the desired data. In many applications, one must look through a sorted tree structure to determine the responsible node for accessing or storing the data. Examples include object tracking in sensor networks, packet routing over the internet, request processing in publish-subscribe middleware, and query processing in database systems. When the tree structure is larger than the CPU cache, the standard implementation potentially incurs many cache misses for each lookup; one cache miss at each successive level of the tree. As the CPURAM gap grows, this performance degradation will only become worse in the future. We propose a solution that takes advantage of the growing speed of local area networks for clusters. We split the sorted tree structure among the nodes of the cluster. We assume that the structure will fit inside the aggregation of the CPU caches of the entire cluster. We then send a word over the network (as part of a larger packet containing other words) in order to examine the tree structure in another node’s CPU cache. We show that this is often faster than the standard solution, which locally incurs multiple cache misses while accessing each successive level of the tree. The principle is demonstrated with a cluster configured with Pentium III nodes connected with a Myrinet network. The new approach is shown to be 50% faster on this current cluster. In the future, the new approach is expected to have a still greater advantage as networks grow in speed, and as cache lines grow in length (greater cache miss penalty). This can be used to successfully overcome the inherent memory latency associated with cache misses.

Notes

Originally published in Proceedings of the 2005 IEEE Computer Society International Conference on Cluster Computing, pp.1-10, Sept. 2005. doi: 10.1109/CLUSTR.2005.347047

Keywords

CPU cache, local area networks, query processing

Subject Categories

Querying (Computer science)

Disciplines

OS and Networks

Publication Date

9-2005

Rights Information

Copyright 2005

Restrictions

Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.

Rights Holder

IEEE

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